A network that helps people worldwide obtain rapid advice and information on crop protection, including the identification and management of plant pests.
PestNet is a network that helps people worldwide obtain rapid advice and information on crop protection, including the identification and management of plant pests. It started in 1999. Anyone with an interest in plant protection is welcome to join. PestNet is free and is moderated, ensuring that messages are confined to plant protection.
Non-Pests > Conservation > Monarch butterfly conservation – more milkweed
February 2015. A post was sent to Pestnet on the conservation of the monarch butterfly (see below). The problem so it says in the article is that the food plant, a milkweed, is being depleted because of the herbicides used by agriculture. A plan to grow more milkweed will be supported by a government grant. The aim is to restore or protect some 200,000 acres of monarch habitat on public and private lands, and to involve schools in the scheme across the country.
A member in New Zealand wrote in response:
According to literature, the Monarch butterfly feeds solely on Gomphocarpus physocarpus, swan plant or balloon plant, which is a species of milkweed that grows on road sides and waste areas. Not to be confused with the Milkweeds Euphorbia helioscopia and Euphorbia pelpus which are significant weeds in agriculture, horticulture and in the home garden and often referred to as Common milkweeds. These species are commonly treated with various herbicides to reduce crop competition.
In the wild, non home-garden situations areas, Gomphocarpus usually grows at elevations of 800m to 1500m as a roadside plant. The seed pods contain floss (fluffy down) which during WW2 was substituted for Kapok filling in life-vests as access to Kapok growing countries had been cut off by the Japanese. A small amount of this floss is still used commercially but obviously the plant has less commercial relevance in 2015 than it did many years ago – perhaps a reason for the decline in Monarch numbers.
In New Zealand we have the swan plant Gomphocarpus fruticosus which apparently hybridises with G. physocarpus and is also fed on by the Monarch Butterfly. It grows to about 2m in height and is a plant commonly grown in the home garden specifically for the purpose of breeding Monarch butterflies.
Website literature states that both species of Gomphocarpus originate from Africa, and if this is correct the USA Monarch butterfly migration to Mexico must be a relatively recent phenomenon – at least as recent as the introduction of Gomphocarpus to the USA by European settlers.
Therefore, he wondered if this sad news about declining Monarch Butterfly Migration is just pure sentimentalism rather than a significant ecological catastrophe that needs to be averted.
In New Zealand, there are a few Asclepias species, other than Gomphocarpus, with Asclepias curassavica ias ther only alternative, so we are very reliant on the home gardener to provide a food source for monarch caterpillars, and our temperate climate allows Gomphocarpus to grow perennially in many places.
A few other species are identified as Monarch caterpillar food sources also but at least one of these is a noxious weed ie Moth plant Araujia sericifera, which therefore cannot be propagated.
Over-wintering occurs in Nelson in the Northern part of the South Island where monarch butterflies congregated in their hundreds (maybe thousands). They were high up in a huge coniferous tree in one of the city parks in early July.
A clarification came a scientist in the US, who made the following comments:
Danaus plexippus subspecies plexippus is the butterfly whose numbers have declined in North America, and North America is its native range.
There are over a hundred native North American species of milkweed in the genus Asclepias most of which host monarchs. Gomphocarpus is only grown in mainland US as an introduced ornamental that doesn’t survive freezes.
Those monarchs throughout the Pacific are generally thought to be a recent (last few hundred years) diaspora from North America (although see Zhan et al. 2014, citation below, for molecular hints of longer residence).
Pestnet member Myron Zalucki has done the most detailed work on when and how monarchs arrived and spread in the Pacific. Most biologists think that monarchs couldn’t have become established until the pan-tropical distribution of non-native milkweeds such as Gomphocarpus with global trade in the colonization era.
You can read the Petition for listing the monarch under the Endangered Species Act here, http://www.centerforfoodsafety.org/files/monarch-esa-petition-final_77427.pdf, to see why we are concerned, with an appendix on the far-flung populations that has as much information as I could find. (I helped write this petition for Center for Food Safety.) A couple of Zalucki’s studies on this are: Zalucki MP, Clarke AR (2004) Monarchs across the Pacific: the Columbus hypothesis revisited. Biological Journal of the Linnean Society 82: 111–121. Available from: http://onlinelibrary.wiley.com/doi/10.1111/j.1095-8312.2004.00322.x/full. Clarke AR, Zalucki MP (2004) Monarchs in Australia: on the winds of a storm? Biological Invasions 6: 123–127. Available from: http://link.springer.com/article/10.1023/B%3ABINV.0000010120.29634.db. And recent molecular biology on monarch genetic differences in locations around the world from whole-genome sequencing (pretty amazing), with Zalucki as coauthor, is: Zhan, Shuai, Wei Zhang, Kristjan Niitepõld, Jeremy Hsu, Juan Fernández Haeger, Myron P. Zalucki, Sonia Altizer, Jacobus C. de Roode, Steven M. Reppert, and Marcus R. Kronforst. “The genetics of monarch butterfly migration and warning colouration.” Nature 514, no. 7522 (2014): 317-321.
From the Huff Post http://www.huffingtonpost.com/2015/02/09/monarch-habitat-fish-and-wildlife_n_6648022.html
Government Pledges $3 Million To Save Monarch Butterfly
Posted: 02/09/2015 7:17 pm EST Updated: 02/10/2015 10:59 am EST
WASHINGTON — The U.S. Fish and Wildlife Service and environmental partners announced a program Monday aimed at regrowing critical habitat for the imperiled monarch butterfly.
The Fish and Wildlife Service is committing $2 million to the plan, while the National Fish and Wildlife Foundation, an organization created by Congress that devotes public and private funds to conservation work, is committing $1.2 million. The National Wildlife Federation is also involved with the campaign.
At an event unveiling the initiative, Fish and Wildlife Service Director Dan Ashe said it will “ensure a future for this iconic species.” The funds are slated to be used to work with schools, community groups, businesses and local governments to create “oases for monarchs in communities across the country.” The goal is to restore or protect 200,000 acres of monarch habitat on public and private lands, as well as build 750 habitats and gardens at schools across the country.
Monarchs are found in many parts of the U.S. and Canada in the spring and summer, and are known for their annual migration south for winter. Their numbers have declined sharply in recent years: 1 billion were counted in Mexican wintering grounds in 1996, but just 35 million were counted last year — the lowest number ever recorded.
“Reversing the decline won’t be easy, but we can do it,” Ashe said. “If we make the habitat, monarch butterflies will come.”
“Sooften in [Washington], problems seem intractable,” National Wildlife Federation President Collin O’Mara said. “Saving the monarch is actually a problem we can solve.”
The butterflies rely on milkweed plants for food and laying eggs. Environmental groups have petitioned the Fish and Wildlife Service to grant protections to the butterflies under the Endangered Species Act, and in December the agency agreed to undertake a review of whether monarchs should be listed as endangered. In announcing that review, the agency noted that threats to the species “include habitat loss — particularly the loss of milkweed, the monarch caterpillar’s sole food source — and mortality resulting from pesticide use.”
Ashe acknowledged that herbicides and the increased use of herbicide-tolerant crops have contributed to killing off the wild milkweed, noting that “highly efficient weed control” is a main reason for the decline. The use of products like Monsanto’s Roundup, which includes the herbicide glyphosate, and Roundup Ready seeds, which are developed to sustain spraying of herbicides, has been linked to the decline of milkweed. Products containing glyphosate have “triggered a precipitous decline of common milkweed, and thus of monarchs,” according to a report issued earlier this month by the environmental group Center for Food Safety.
But the plan announced Monday focuses on growing milkweed in alternative locations rather than on addressing issues related to herbicides.
“We do very effective weed control in the agricultural production sector in the United States. That’s a good thing. We have efficient, effective production of commodity crops. We all benefit from that,” Ashe said. “We have to look for alternative habitats. We can make alternative habitat for monarch butterflies.”
Ashe said the Fish and Wildlife Service currently does not have plans to undertake regulating the use of herbicides.
“I would say from the standpoint of production agriculture, we all benefit from the availability of abundant, affordable, healthy food,” he said. “So we want agricultural production to be as efficient as it can possibly be so we have to convert less acreage to crop production.”
Larissa Walker, the pollinator campaign director at the Center for Food Safety, said in a statement to The Huffington Post that increased funding for habitat is not enough to protect the butterflies.
“While efforts to restore milkweed habitat are essential to the monarch butterfly’s survival, without addressing the eradication of milkweed within agricultural fields, monarch populations will not rebound to resilient, healthy levels,” Walker said. “Research has shown that monarch butterflies lay up to four times more eggs on milkweed within agricultural fields, and unfortunately, this vital breeding habitat has been destroyed by herbicides used in conjunction with genetically engineered crops.”
Ashe noted that the agency is interested in partnering with herbicide manufacturers, such as Monsanto, in the effort to grow habitat but that it had not approached the company yet.
In a statement to the Huffington Post, Monsanto spokeswoman Charla Lord said there are “multiple reasons milkweed population has declined.” She also listed other issues that are affecting the monarch, such as logging in Mexico’s forest wintering sites, weather events, parasites and climate change.
“We believe there are opportunities for public-private partnerships to expand habitat adjacent to crop lands — and we applaud the announcement of today,” she wrote. “Farming and habitat for Monarchs can co-exist.”
Lord said that the company is “reviewing the announcement today” but is “very interested to exploring how Monsanto and others in the agriculture industry to can help support these initiatives.”
CORRECTION: Due to an editing error, a previous version of this post inaccurately paraphrased a statement from the Monsanto representative on the decline of the monarch.